The keeper position has often been a cause for reported internal squabbles at Madrid over the last year or so, starting with Kepa Arrizabalaga last season.
Madrid's hierarchy were said to have lined up a move for Kepa from Athletic Bilbao, but the deal ultimately fell apart due to Zidane's apparent misgivings and his trust in Navas.
The club's seeming lack of faith in Navas again looked apparent after Zidane left the club last May, as they brought Courtois in from Chelsea for a reported €35million fee after David de Gea became unattainable and the Belgian became first choice under Julen Lopetegui and then Santiago Solari.
However, Courtois has had an underwhelming season by his usual lofty standards and has been dropped in favour of Navas since Zidane's return, with recent reports of the former Atletico Madrid star being put up for sale unlikely to be cooled by the coach's latest comments.
Speaking ahead of Thursday's trip to Getafe, Zidane said: "As always, I will not tell you [the media] what I want. Sometimes I want things, they do not happen, just the opposite.
"You want to talk about the goalkeepers, but it is not the moment to talk about that. Courtois is available with Keylor, and Luca [Zidane] isn't, that's it.
"The goalkeepers all have contracts. It is my responsibility [to choose], you will see who plays over the last five games.
"This is not the moment to talk about this, but next year it will all be very clear for everyone.
"I'm not going to answer [whether he will rotate between LaLiga and the Champions League]. You'll find out next year.
"I was saying it recently, I have the best two [goalkeepers] and a young one who is good and has a future.
"Keylor and Thibaut are very good. It's easy for you, but complicated for me when I have to choose, and not only in terms of the goalkeepers, but in general when everyone is available."
Zidane was then asked if he would understand why one of Navas or Courtois might ask to leave the Santiago Bernabeu should it become apparent they will be second choice, and the coach appeared to open the door to such a situation.
"Anything can happen," he said.